Post-transplant malignancy - The role of immunosuppression

Immunosuppressed organ allograft recipients have a 3- to 4-fold increased r isk of developing tumours, but the risk of developing certain cancers is in creased several hundredfold. With the exception of skin and lip cancers, mo st of the common malignancies seen in the general population are not increa sed in incidence. Instead, there is a higher frequency of some relatively r are tumours, including post-transplant lymphomas and lymphoproliferative di sorders (PTLD), Kaposi's sarcoma (KS), renal carcinomas, in situ carcinomas of the uterine cervix, hepatobiliary carcinomas, anogenital carcinomas and various sarcomas (excluding KS). Skin and lip cancers present some unusual features: a remarkable frequency of KS, reversal of the ratio of basal to squamous cell carcinomas seen in the general population, the young age of t he patients, and the high incidence of multiple rumours (in 43% of the pati ents). Anogenital cancers occur at a much younger age than in the general p opulation. Salient features of PTLD are the high frequency of Epstein-Barr virus-related lesions, frequent involvement of extranodal sites, a marked p redilection for the brain and frequent allograft involvement. As the immunosuppressed state per se and various potentially oncogenic viru ses play a major role in causing these cancers, preventative measures inclu de reducing immunosuppression to the lowest level compatible with good allo graft function and prophylactic measures against certain virus infections. Reduction of exposure to sunlight may also decrease the incidence of skin c ancer. In addition to conventional treatments (resection. radiation therapy , chemotherapy) patients may receive antiviral drugs, interferon-alpha and various other manipulations of the immune system. A significant percentage of cases of PTLD and KS respond to reduction or cessation of immunosuppress ive therapy.